200mph in a Bentley GT Speed!

Pat Devereux takes a cruise along the boulevards of Beverly Hills before a 200mph blast along a deserted runway...

In 1923, Cheshire-born mountaineer and explorer George Mallory was asked by a New York Times reporter why he was bothering to attempt climbing Mount Everest. It seemed like such an impossible task that it could only end in disaster, he had to hear why Mallory and his team were even thinking of doing such a ridiculous thing. "Why?" said Mallory fixing his steely gaze on the writer. "Because it's there."

Ninety years to the day, I'm sitting in a Cheshire-built Bentley Continental GT Speed Convertible, engine wuffling away like a contented dray horse, at the end of a 2.9-mile runway in the high Californian desert, seconds away from trying something similarly questionable. Seeing how fast you can go in a four-seat convertible with the roof down. Why? Because I can.

Pulling the finely crafted gearstick back into the S position, there's a small click from the rear as the exhaust valves open and the sound at the twin tailpipes drops a couple of notes from its normal syrupy bass to the full Barry White. Other than doing up my seatbelt and lowering the roof, that concludes the preparation for this unofficial record attempt.

Which is one of the key reasons why we like this Bentley - all Bentleys, actually - so much. There aren't any limiters telling you what you can and can't do. If you want to use all of the engine's performance, you can, whenever and wherever you think it's safe(ish) to do so. If you want to programme a destination into the satnav while you're moving, you can. If you want to eat the seats, there's no legal warning labels - go ahead, you can do that, too. The message is clear: it's your car, you're a grown-up, do what you like with it.

Which includes setting records no one has ever even thought about attempting. Like the one I'm about to do.... NOW. Flattening the throttle into the carpet, the eight-speed gearbox immediately gets the message that full steam ahead is required and hangs onto every gear right up to the red line. With four-wheel drive and the super-grippy runway surface, there's no tyre noise or savage change in the 2.5-tonne car's attitude. We are just surging towards the horizon, slightly uphill, at an ever-increasing rate of knots.

Four seconds in, we are past 60mph, and, with the weight of the car now not so much of an issue, it's lunging forward at an almost comedic rate. It's hitting higher and higher numbers as fast as I can say them: 110, 120, 130, 140, 150, 160... and, even without the wind deflector in place, I'm hardly buffeted by the wind. An MX-5 at 60 is worse than this. 170, 180, 190... it's slowing a bit now, but hasn't given up. There's still plenty in the tank.

Which, with 200mph looming, is probably a good time to suspend the proceedings for a few moments and rewind a bit to explain more about this extraordinary convertible car.

Until last month, the V8-powered Bentley Continental GT was clearly the model to have in the Bentley range. Combining all the power you could need with all the gentleman's-club luxury you expect in a Bentley, it uses appreciably less fuel and costs less to buy. So it immediately made the W12-powered cars seem redundant.

Then the new, 616bhp W12-engined Continental GT Speed turned up. And before we'd even got into it, we knew it was going to be a little more right than any other Bentley before it. Riding on 21-inch wheels with 10mm lower suspension, there is a tightness and rightness to the look of it, like a huge mechanical toad hugging the road, ready to leap forward at a moment's notice.

Then we drove it and, within a couple of miles, knew this was now the sweet spot in the Bentley range. It might have seemed like an entertainingly odd thing to do, to turn one into a rally car, like James did. But once you've driven one for a while, it doesn't seem like such a crazy idea at all. If you were ever going to rally a Bentley, this'd be the one. It's by far and away the best-balanced of the new breed, with the finest steering, the biggest brakes and the most sophisticated gearbox. It's got AWD, so, true to the Bentley spirit, why not?

The GT Speed Convertible doesn't change any of the saloon's mechanical spec, just adds the bits you need to enjoy the performance al fresco. Like a four-layer fully automatic roof and a manual wind deflector. This conversion adds 175kg to the kerb weight, reducing top speed by 3mph to 202mph, making 0-60mph take a couple of ticks longer, at 4.1 seconds, and increasing fuel consumption. But the boot is still a usable size. Which is more than can be said for the rear seats, which aren't.

To make up for those, the front seats go out of their way to make sure you are sitting comfortably. Apart from the exquisite quilting and stitching, they have a zillion adjustments in every imaginable direction, heaters, coolers, massagers and a new bit - a vent that directs air of any temperature you like to your neck. So, however picky you are, you absolutely will be able to find a setting to suit you and the weather.

The important part about all the Speed's performance enhancements is that they do not affect the car's ability to waft in proper convertible Bentley fashion. Set the damping in Comfort, peel back the roof and it'll wuffle around in super-luxury style. At normal road speeds, there's little more than a wisp of air in the cabin, with or without the wind deflector in place. The only minor irritation is the squealing from the racing compound brake pads. But I'm sure you can option those and their noise away.

The really impressive bit is what happens when you decide to use the Speed bit of the car's name. Instead of slipping imperceptibly between gears, the eight-speed ZF gearbox and engine management has been tuned to block downshift from eighth to as low as fourth almost immediately. We've driven this gearbox in everything from new Jags to Jeeps, and it always works well - thanks to its 99 available programmes, apparently - but never quite so sweetly as in this big Bentley. No thinking or hesitation, just instant warp drive when you want it.

Which, back at Naval Air Station Lemoore's 2.9-mile runway, is now...

At 195mph and still accelerating, with the end of the runway coming towards me at nearly 100m per second, I glance down at the speedo, and there, in orange Gill Sans Bentley typeface, is a polite message from the boys in Crewe. I can't remember the exact wording, but it was something like: "Terribly sorry to disturb you, old boy, but just thought you might like to know that if you are thinking of keeping up this sort of speed, you might want to add a spot more air to the tyres. Pip pip."

Ah, the tyres. I've forgotten to adjust the pressures for high-speed running - the only thing you have to get out of the car to do. Currently, the P Zeros have about 15psi less all round than the recommended figure. Which might be why the Speed has got a very slight wiggle on. I'd been blaming it on a crosswind, but, now I've seen the polite message, I know what it is. Might be time to slow down and turn off the seat-heaters, which, when I go to adjust them, I realise aren't on.

As irritating as the brake noise can be with the top down in town, when you want to haul the car back to sane speeds, it's not something you notice or care about when doing almost 200mph. The main concern, particularly on this super-grippy surface, is that your eyeballs are going to detach and hit the windscreen. Only an aircraft carrier has more stopping power than this car.

Returning to the start line to add some more air to the tyres and have another go, the Speed reverts to its normal, relaxed, cuddly self again. It's used a couple of gallons of fuel in just one run, but the engine temperature hasn't budged, and all the other vital signs are normal. It feels like it could do this all day. And, as physically unruffled as I am by the experience, so do I.

So, in the spirit of George Herbert Leigh Mallory, we do. He never made it to the top of Everest back in 1924, but we do manage to crest 200mph - our unofficial goal - more than once later that day. Why do it more than once? For no other reason than, in a Bentley Continental GT Speed Convertible, unlike any other 2,500kg four-seat convertible, you can. We think George would have approved.

Words: Pat DevereuxPhotography: Drew Phillips

This feature was originally published in the April 2013 issue of Top Gear magazine